The present invention relates in general to heated tools and, in particular, to a new and useful apparatus for connecting one part to another by heating the parts, which includes a heating bar, means for moving the heating bar into engagement with one of the parts and in a direction toward the other part, and stop means for stopping the movement of the heated tool when it reaches a selected distance from the other part. The heating tools may either be moved to the objects to be treated, or connected, or mounted in a fixed position with the object to be treated, or connected being brought to the heated tool.
Thermal energy is either supplied to the objects to be treated, or connected by radiant heating from heated surfaces of the tool, or by direct thermal contact between the heated tool and the object. A controlled force is usually applied against the object by the heated tool. An additional thermal conductive material may be used to increase heat flow from the heated tool to the object. Flux, for example, may be provided, for increasing the transfer of heat and for reducing oxidation during the thermal process.
Such tools may supply heat either continuously or during selected time periods only. Heat may be applied during heating pulses, which may be activated or controlled by various external conditions, for example, by forcing the heated tool against the object to be heated or connected.
Various sources of heat are known for heating the heated tool to a variety of selected temperatures. Hot gases and/or electric current, for example, may be used for heating specified heat supplying areas or surfaces of the tool.
For the present invention, it is preferable to utilize the flow of electrical current through a heated tool for heating the tool. This permits controlled pulse-heating featuring fast heating rates, as well as precise temperature control at various areas of the tool.
A known generally U-shaped heated tool is disclosed in German Patent reference No. 2,848,519. This heated tool is mounted to holders, either using screws or by welding. This keeps the heat supplying areas of the tool in position and further is used to provide electrical connectors for feeding electrical heating current to the tool. Such tools can be manufactured using sheet metal designs (see German Patent Nos. 3,144,048.7, 3,137,859.5 and 3,137,860.9 to the present inventor). These heated tools can also be machined from solid materials.
When transferring thermal energy to one or more objects using one or more heated tools, excess heat and relatively long periods of time are sometimes needed, particularly when the objects are made of materials having high thermal loads.
Referring to FIG. 1, a U-shaped, heated tool is shown, which includes a heating bar 2 that is mechanically supported and supplied with current by support bars 1. The heating bar 2 has a heating surface 3 which is brought into contact with a round wire 4 in the direction of arrow F. Sufficient force is applied to round wire 4 to bring it into close thermal contact with a metalized layer or substrate 5 on a support material 6. If support material 6 is sensitive to heat, a danger exists of damaging material 6 if too much force and/or too much heat is supplied to the parts 4 and 5 to be connected together.